The index closed 35.13 points lower after losing 2.27 points on Friday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 9.65% to VND9.98 trillion ($422.75 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 29 tickers dropped.
Eight blue chips closed at floor price, including GVR of Vietnam Rubber Group, MWG of electronics retail chain Mobile World and NVL of property developer Novaland Group.
Other decliners include VIB of Vietnam International Commercial Bank, down 6.6%, and VPB of private lender VPBank, down 6.3%.
GAS of state-owned Petrovietnam Gas was the only blue chip that gained this session with a 1.1% rise.
Foreign investors were net buyers to the tune of VND437.37 billion, mainly buying HPG of steelmaker Hoa Phat Group and VCB of state-owned lender Vietcombank.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 3.31% while the UPCoM-Index at the Unlisted Public Companies Market was down by 1.83%.